Preheat to 350°F (175°C). Lightly grease a 9×13-inch casserole dish.
In a large bowl, stir together uncooked rice, both soups, broth, milk, garlic powder, onion powder, salt, and pepper until smooth.
Fold in cooked chicken and 1 cup of cheddar. Mix until evenly combined.
Pour mixture into the dish and spread evenly.
Sprinkle more shredded cheddar over the top.
Mix panko with melted butter, then sprinkle over the cheese.
Cover with foil and bake for 30 minutes. Uncover and bake 15 more minutes until bubbly and golden.
Let rest 5–10 minutes before serving to help it set.